Method of constructing foundation piles



Aug. 15, 1939 R. BERTRAND METHOD 0F CONSTRUCTING FOUNDATION PILEIS Filed April l Vwr/ 6' l Al."

Patented Aug. 15, 1939 P-TENT OFFICE METHOD F CONSTEUCTING FOUNDATION PILES Raymond Bertrand, Brussels, Belgium, assigner to Compagnie Internationale des Pieux Armes Frankignoul, Socit Anonyme, Liege, Belgium Application April l., 1937, Serial No. 134,421 In Belgium April l, 1936 2 Claims.

My invention relates to a method of constructing foundation piles, more particularly from reinforced concrete, moulded in the ground by means of a preparatory or lining tube, the latter if being withdrawn in measure as the concretingvof thevp-ile is proceeded with. The method is more particularly devised for use in constructing piles in grounds where underneath pressure is present which tends to force back the concrete into the inside of thetube.

One of the most suitable methods among those known for moulding the shaft cf a foundation pile, by the aid of a preparatory tube7 in a ground in which high underneath pressure is present, consists in ramming the concrete outwardly of the tube while withdrawing the latter, or in eiecting simultaneously the ramming of the concrete and the withdrawal of the tube. Consequently, the'latter is being raised while the monkey is acting upon the concrete poured into the tube, the arrangement being such that if the monkey is inoperative during the step of pouring concrete into the tube, the withdrawal of the latter is Vinterrupted during the same step.

stopped by firmly rammed concrete the friction of which against the inner wall of the tube opposes the action ofthe underneath, upwardly acting pressure.

It will be granted that the described method is .reliable and practical. However, if the underneath pressure is very high, it is necessary, in order tooppose the action of such pressure, to permanently keep up in the preparatory tube a mass of compressed concrete of relatively great height. In the arrangement described, the blows of the monkey are mainly effective in ramxning the concrete contained inside the tube, while the action of the blows upon the concrete outwardly of the tube is relatively weak. It may then occur that the diameter of the pile be not substantially greater than the inner diameter oi the preparatory tube, Where the lower end of the tube is provided with an inwardly extending strengthening shoulder-for the purpose of increasing the resistance of the latter to radial strains produced by the blows of the monkey upon the mass of concrete-the diameter of the inished pile will be still further reduced.

According to my invention, a pile having a diameter at least equal to the outer diameter of the lining tube proper may be constructed in ground of the character specified by using a lining tube the lower end of which is provided with an extension member integral with the tube and having an The lower end of the tube is thus permanentlyk inner diameter greater than the inner diameter of the lining tube proper, and by carrying out the concreting of the pile in successively compressing batches of concrete inside the extension member, until the required nal degree of cornpression is reached, each charge of concrete thus compressed being driven out and into the ground during the withdrawal of the lining tube structure, and while the ramming is carried on.

The extension member may consist ofv a length of tube embracing the lower end of the lining tube proper and welded, riveted or bolted to, and extending for a certain distance beyond such end, the upper edge of the extension member being provided with a tapered surface suchas u may be formed by the added metal of an annularr welding joint connecting the extension member to the lining tube proper.

The provision of the extension member or sleeve results in no impediment during the sinking or the withdrawal ofthe lining tube structure into or from a ground in which underneath pressure is present, considering that grounds of such character are soft. However, care should be L taken that the extension member does not penetrate entirely into a compact underground stratum, since, otherwise, the withdrawal of the preparatory tube structure would become more difficult.

The compressed concrete contained in the extension member or added length of tube eiiciently opposes the action of the underneath pressure, even if there is no compressed concrete inside the lining tube proper. In fact, the restriction in cross area at the point of the inner junction between the extension member and the lining tube proper, prevents the concrete from being forced back into the latter and the action of such lconcrete is more eicient than that exerted by the relatively important quantity of concrete which is left in the preparatory tube according to the conventional methods. Water mud, slime, shifting or quicksand which may be found in the ground are thus prevented from entering the 1ining tube structure, and even from mixing with the concrete of the pile, since the lower portion of. the extension member remains stopped by firmly rammed-concrete. Thus, I may substantially reduce the height of, and even entirely dispense with, the mass of concrete rammed inside the 1ining tube proper. It will therefore be seen that, for securing a predetermined diameter of pile and a predetermined degree of compression of concrete, the degree of compression of the concrete inside the extension member will be sub- 55 stantially smaller than that which was required inside the lining tube according to the conventional methods. Moreover, since, according to my invention, the head of concrete rammed inside the lining tube proper may practically be dispensed with, the frictional adherence of the concrete to the wall of the preparatory lining tube structure which must be overcome during the driving out of the compressed concrete, will be greatly reduced.

From the foregoing it will be understood that my invention results in materially reducing the power required for ramming and driving out the concrete and for withdrawing the lining tube structure.

Finally, it will be noted that where a reinforcing assembly is inserted into the preparatory lining tube structure, such assembly will be entirely encased with the concrete forced into the extension member, and will therefore be exactly centered. Consequently, a reinforcing assembly having a diameter substantially equal to the inner diam.- eter of the lining tube proper may be used. thus enabling the assembly to be positioned nearer to the periphery of the pile, with a resulting more effective reinforcement of the latter. Further more, the reinforcing assembly is self-centered, without resorting to centering expedients.

By way of example, one embodiment of the object of my invention will be hereinafter described with reference to the accompanying drawing, which shows a fragmentary central section of the preparatory tube structure during the process of forming a reinforced concrete pile.

The lower end of the tube i is embraced by a sleeve or length of tube 2, 2a, the portion 2c of which fits around the tube Il` while the lower portion forms the extension of latter, The sleeve is rigidly connected to the tube I. for example by an outer welding joint as at 3 and by an inner welding joint as at 5. The welding me al ring 3 forms a taper which will make still easier the withdrawal of the tube. Where the sleeve is fitted to the tube by riveting or bolting, the upper edge of the sleeve may be beveled for the same purpose.

The tube I, being fitted with the sleeve is driven. into the ground by any suitable method, such as by applying the blows of a monkey upon a plug of compressed concrete, which is formed in the lower portion of the tube structure and tightly fitting thereto, and which takes the latter with it due to its high frictional adherence to the inner wall of the tube structure. An enlarged base portion for the pile may then be established by ramming suitable materials in the ground.

The concreting of the shaft of the pile is then effected in the following manner. After the basket-like reinforcing assembly 5 has been placed in position, the required quantity of fresh concrete is poured into the lower portion of the lining tube structure. The fresh concrete is then subjected to the blows of the monkey 6 until the desired degree of compressionv is' reached. Upon achievement of the ramming operation, the mass of compressed concrete may, as shown at 'I in the case illustrated by the accompanying drawing, be entirely contained inside the extension member 2, or again, may partly protrude into the tube I a relatively small distance. A new charge of concrete 8 is then introduced into the preparatory tube structure and ramming is carried on by means of the monkey 6, while progressively withdrawing the tube I, so as to drive out from the extension member the concrete which has been compressed therein, and simultaneously to force the concrete contained in the lower portion of the tube I out of the latter and to expand laterally in the extension member 2.

The charges of concrete driven out in succession from the extension member 2 by repeating the steps above described, form the shaft 9 for the pile which will have a diameter at least equal to the outer diameter of the lining tube proper I.

It will be noted that the reinforcing assembly 5, which has a diameter substantially equal to the inner diameter of the tube I proper, is entirely encased within the concrete forced into the extension member 2 and remains self-centered.

What I claim is:

1. A method of constructing foundation piles in the earth wherein underneath pressure is presend by the aidofapreparatorytubehavingatubular extension member embracing the lower end thereof which comprises, driving the tube into the ground to the desired depth, introducing a rst charge of concrete into the tube and compressing the charge within the extension member until the required final degree of compression is obtained so as to force the concrete of the rst charge against the inner wall of the extension member before withdrawing the tube, and thereafter concreting the body of the pile by compressing successive charges of concrete within the extension member until each charge has received the nal required degree of compression and driving each batch of concrete out of the tube after compression while the preparatory tube is withdrawn a distance for receiving the next batch of concrete.

2. A method of constructing foundation piles in the earth wherein underneath pressure is present by the aid of a preparatory tube provided at its lower end with a rigid extension member haviing an inner diameter equa-l to the outside diameter of the tube which comprises, driving the tube into the ground to the desired depth, arranging a reinforcing assembly adjacent the inner diameter of the tube, introducing a first charge of concrete into the tube and compressing the charge within the extension member until the required nal degree of compression is obtained so as to move the concrete laterally against the inner wall of the extension member and encase the reinforcing assembly before withdrawing the tube, and thereafter concreting the body of the pile by compressing successive charges of concrete within the extension member until each charge has received the nal required degree of compression and driving each batch of concrete out of the tube after compression while the preparatory tube is withdrawn a distance for receiving the next batch of concrete.

RAYMOND BERTRAND. 

